1. Field of the Invention
The present invention relates to a developing unit that forms uniform thin film of toner on a developer carrier and supplies toner to a latent image carrier and, more particularly, to a high voltage power supply apparatus that applies a voltage to the developer carrier, latent image carrier, and a restricting blade that constitute the developing unit and an image forming apparatus that uses the high voltage power supply apparatus.
2. Description of the Related Art
It is necessary to apply an adequate bias voltage respectively to the developer carrier, latent image carrier, and restricting blade that constitute the developing unit by the high voltage power supply apparatus. For example, Japanese Patent No. 3264001 discloses a configuration in which, in a developing unit constituted by a developing roller (developer carrier), a blade (layer thickness restricting means), and a reset roller (supply means), while a voltage is applied from a blade (layer thickness restricting means) application power supply to the blade (layer thickness restricting means), toner is transferred to the developing roller by an electrostatic force of a toner supply electric field directed from the developing roller to the reset roller generated between the potential (supply means application voltage) of the reset roller which causes friction between the toner to thereby preliminary charge the toner negatively and to which a supply means application voltage, in which a DC component and AC component are superimposed, is applied by a supply means application DC power supply and a supply means application AC power supply and potential (developing bias voltage) of the developing roller applied by a developer carrier application power supply.